Sizing composition and yarn sized therewith



Patented Sept. 3, 1946 SIZING COMPOSITION AND YARN SIZED I THEREWITHHarry R. Dittmar, Wilmington, Del., assignor to E. I. du Pont de Nemours& Company, Wilmington, Del., a corporation of Delaware No Drawing.Application August 4, 1943,

Serial No. 497,366

This invention relates to a sizing composition and yarn sized therewith.More particularly, this invention relates to a sizing compositionsuitable for nylon yarns intended for the knitting of full-fashionedhosiery, and nylon yarn sized therewith. I

It is known that the proper sizing of nylon yarn for use in the knittingof full-fashioned hosiery is a very critical operation. The basicrequirements include 1) good knitting performance, even at highhumidities, (2) good stitch formation, (3) no marked tendenc ofedge-rolling of the flat fabric since this makes seaming slow andexpensive, and (4) excellent snag-resistance of the fabric throughoutthe several processing steps. One of the most successful of the sizingcompositions available for nylon yarns is that described in U. S. patentof Edgar W. Spanagel, No. 2,324,601, issued'Juily 2U, and which consistsof partially hydrolyzed polyvinyl acetate (known in the trade aspolyvinyl alcohol) modified with a substantialbut minor proportion of'boricac'id. 'Even this composition gives quite poor knittingperformance under conditions of high humidity. This turns out to be aserious matter since high humidities prevail along the eastern seaboardfor a considerable part of the year. Moreover, since it is goodpracticein knitting full-fashioned hosiery from silk to well humidifythe yarn at the moment of knitting by passing it over a wick laden withwater or through a chamber at 100% humidity, there is a strong tendencyto do the vsame when Working with nylon yarn. The resultis that theability to knit well at high humidities without depositing size on orfouling the knitting needles becomes the first criterion of a goodknitting size.

It is an object of, this invention to provide an improved sizingcomposition for nylon yarn to be used for the knitting of full-fashionedhosiery. Another object of this'invention is to provide sized nylon yarnthat will'give good knitting performance even under conditions of highhumidity. A specific object of this invention is to improve thepolyvinyl alcohol-boric acid size so that nylon yarn sized therewithwill knit Well even at high humidities without depositing size on orfouling the needles or sinkers of the knitting machine. Other andadditional objects will become apparent hereafter.

The objects of the invention are accomplished, ingeneral, by modifying apolyvinyl alcohol-boric acid size by incorporating therein a modifiedpolymer of dioxolane. 'The following examples are typical embodiments ofthe invention, and it is 20 Claims. (Cl. 260-32) midity as knittingproceeds.

to be understood that the invention is not restricted to the specificdetails thereof, the parts, proportions and percentages being by weight:

Example I A size composition of the following ingredients in theproportions set forth is prepared in any convenient manner:

Parts In the polydioxolane sebacate, the ratio of combined sebacic acidto'combined 1,3-dioxolane is 1:8, and the of about 1500 and a hydroxylnumber of 61.7.

Single ends of 30 denier-1G filament-3O turn polyhexamethylene adipamideyarn is sized in conventional fashion with this composition to give afinal yarn having 3.6% size and dried at 80 F. and 50% relative humidityfor 9 hours. The yarn is twist-set in ovens at a dry bulb of 170 F. anda wet bulb of 165 F. for 2 hours, and thereafter conditioned at 72%relative humidity for 10 hours. It is finally coned, using a typicalconing oil for nylon. It is knitted using a gauge, single-end Wildmanflat knitting machine, the yarn being conditioned at 100% relative hu-The yarn runs very well through the knitting machine, leavingpractically no deposit on the needles and latches even after severaldays operation. The knitted stitches are well formed. The flat fabricremains substantially flat so that the seaming operation proceeds in amanner fully equal to the experience with natural silk. Overall millperformance shows a small percentage of pulled stitches due to.snagging.

' Example II A composition of the following ingredients in theproportions set forth is prepared in any convenient manner:

Parts Polyvinyl alcohol-boric acid 6 Polydioxolane adipate 4 Watercompound has a molecular weight 7 water.

properly chosen, the resulting polymer will not r A composition of thefollowing ingredients in the proportions set forth is prepared in anyconvenient manner:

- Parts Polyvinyl alcohol-boric acid 3.5 Polydioxolane stearate 2.5Water 94.0

In the polydioxolane stearate, the ratio of combined stearic acid tocombined 1,3-'dioxolane is 1:8, and the compound has a molecular Weightof about 1200 and a hydroxyl number of 59.

Single ends of 30 denierfilamentturn polyhexamethylene adipamide aresized, dried, twist-set, conditioned "and coned as set forth in ExampleI. The yarn is then knit as set forth in Example I except that the yarnis conditioned for knitting at a relativehumidity of 50%, which istypical of certain parts of the year along the eastern seaboard.Completely satisfactory performance results.

The polyvinyl alcohol-boric acid of each of the above examples is apartially saponified polyvinyl acetate (known in the trade as polyvinylalcohol) having a 'saponification number of 140 and a viscosity of 4centipoises, modified with 20% boric acid based on the polyvinylalcohol.

Though the examples refer to specific modified polymers of dioxolane,the invention is not restricted thereto. There may also be used polymers of dioxolane modified by other monobasic or polybasic carboxylicacids or esters thereof and prepared, for example, by (1) effecting thepolymerization of the dioxolane in the presence of carboxylic acid,using a strong acid such as. sulfuric acid for the catalyst; (2) firstpolymerizing thedioxolane in the presence of a strong acid such assulfuric acid and then reacting it with an ester of the carboxylic acid,using an alkaline catalyst to obtain an alcoholysis reaction; and

(3) first reacting dioxolane with the carboxylic acid to obtain a lowermolecular weight polymer than desired and then subjecting this polymer.to further reaction with dioxolane to obtain a higher molecular weightpolymer. Similarly, substituted dioxolanes may be used as a startingmaterial, and these include such compounds as the 2-ethyl and the2,2-dimethyl 1,3-dioxolane. In general, the molecular weight of themodified dioxolanepolymer should be within the range of 500 to 1500. Theratio of combined acid to the dioxolane may vary within quite widelimits. It will .be obvious to one skilled in the art that if the ratioof the acid, such as stearic acid, becomes too large, the resultingpolymer will not be soluble in Similarly, if the ratio of the acid isnot be a solid. The ratio within which water-solubility and a solidstate is developed varies with the particular acid involved and isreadily ascertainable by experiment. In every case, the dioxolanepolymer intended for use with this invention should be a low-melting,waxy solid which is soluble in the water.

For a more detailed discussion of the method of preparation of thesemodified polymers of dioxolane, reference may be had to copendingapplication Serial No, 395,366, filed May 2'7, 1941. In the foregoingexamples, preference has been 4 shown for a specific partiallysaponified vinyl acetate which is soluble or emulsiflable in water andwhich is known in the trade as polyvinyl alcohol. The invention,however, is not restricted to such specific polyvinyl alcohol. Generallyspeaking,- any water-sensitive polyvinyl compound in which 1% .to 50%,and preferably to 50%, of the carbon atoms in the polyvinyl chain areattached to hydroxyl groups (such compounds being herein referred to ashydroxylated polyvinyl resin) can be used. As illustrative examples ofhydroxylated polyvinyl resins which can be used are the partial estersof polyvinyl alcohol such as the partial acetates, thepartial-propionates, the glycolic acid esters, the partial formates, andthe partial lactates; the partial ethers of polyvinyl alcohol such asthe glycol ethers, the glycolic acid ethers, the methyl ethers, and theethyl ethers; the partial acetals of polyvinyl alcohol such as thepartial formal, the partialflacetal, the partial glyoxal, the partialpropional, and the partial .butyral; the partial ketals of polyvinylalcohol such as the ethylmethyl ketal. I

Although partially saponified polyvinyl acetates having saponificationnumbers from to 150 are particularly useful, partially saponifiedpolyvinyl acetates having saponification numbers of between 10 and300,such as 40 to 200, or even somewhat lower than 10 or higher than 300,may be used to advantage. Saponification numbers of the partiallysaponified polyvinyl acetate, as used herein, .are defined as the numberof milligrams of potassium hydroxide required to completely saponify 1gram of the sample.

The partially saponified polyvinyl acetate may have viscosities of 1.5to 20 centipoises, and preferably 4 to 6 centipoises, the viscositybeing determined on'a 4% aqueous solution at 20 C. using a Hoepplerviscosimeter.

In general,'the amount of boric acid can vary within wide limits. Themaximum quantity of boric depends on the characteristics of theparticular hydroxylated polyvinyl resin and is sufficient to insure goodrunning properties but insufficient to cause gelation. Althoughparticularly desirable results are obtained when the boric acidconstitutes approximately 20% to 22.5% of the weight of the polyvinylalcohol, the amount of boric acid can vary between 5% and 25% based onthe weight of the polyvinyl alcohol, the limit depending on thecharacteristics of the particular polyvinyl alcohol and being, on theone hand, sufiicient to insure good running properties and, on the otherhand, insufficient to cause gelation.

When formals of polyvinyl alcohol containing 10% to 30% of formalconstitute the hydrpxylated polyvinyl alcohol, the amount of boric acidmay vary from 5% to 20% based on the weight of the formal.

The proportions of the polyvinyl hydroxylated resin-boric acidcomposition to the dioxolane polymer may be varied within limits. Inmost cases, proportions of 50:50 seem to give optimum 5 results, butquite satisfactory results are' secured within the limits of :35 and35:65.

It is true that the polyvinyl alcohol-boric acid composition by itselfis quite a remarkable size for nylon yarn in terms of edge-rollingprevention and snag-resistance but its running characteristics at highhumidities, as has been previously noted, arenot at all satisfactory.The dioxolanepolymers by themselves have no special sizing value andhave extremely poor snag-resistance. It is quite surprising that theycan so materiall improve the running qualities of the polyvinylalcohol-boric acid composition without impairing the edge-rollingcharacteristics and the snag-resistance.

It will be obvious to one skilled in the art that the sizingcompositions of this invention can be applied by conventional methodsfrom an aqueous solution or dispersion of any desirable concentration toyield on the yarn a coating of any reasonable thickness. Solutions of 2%to 12% total solids content are preferred, depending, as .is known, onsuch factors as the denier and filament count of the yarn, itswater-sensitivity, the rate of travel of the yarn through the sizingbath, the temperature of the bath and of the drying conditions and theamount of size desired on the yarn. It will be obvious too that theamount of size desired on the yarn will var with these or similarfactors. Generally, a coating on the yarn of from 1% to 6% is preferred.

For reasons of simplicity, the invention has been discussed specificallyin terms of polyhexamethylene adipamide yarn since that is the commonnylon yarn of the'market. The invention.

obviously embraces other synthetic linear polyamide yarns as well asrelated synthetic linear polymer yarns, such, for example, as thosederived from polymerizable mono amino carboxylic acids or theiramide-forming derivatives and vthose derived from the reaction ofsuitable diamines with suitable dicarboxylic acids or amide- .formingderivatives of dibasic carboxylic acids, disclosed in U. S. Patents Nos.2,071,250, 2,130,523 and 2,130,948. Without limiting the broad andgeneral definitions of nylon as used elsewhere in patents or literature,the synthetic linear polyamides herein disclosed are defined as setforth in U. S. Patent 2,359,877, i. e. a synthetic linearpolycarbonamide wherein the average number of carbons in the segments ofthe chain separating the amide groups is at least two.

The invention is additionally applicable to any I water-insensitivesynthetic linear polymer yarn, since the compositions employed in thisinvention adhere well to these yarns in contrast to the more well-knowncompositions. By the term water-insensitive, it is meant that theindividual filaments of the yarn absorb less than 10% of their weight ofwater at 25 C. and 100% relative humidity. Examples of such polymers arethe vinyl chloride-vinyl acetate interpolymers, polymerized methylmethacrylate or polymerized 'ethyl methacrylate, polyvinyl chloride,chlorinated polyvinyl chloride, high molecular weight ethylene polymers,vinyl chloride-vinylidene chloride copolymers, and acrylonitrile andcopolymers thereof.

The invention has special value in connection with the knitting offull-fashioned hosiery since that involves ver fine and delicate yarns,careful knitting, the problem of edge-rolling of the fiat fabricwith thedifficulty of seaming, and the chances of snagged and pulled threadsinherent in the many processing steps. The composition of the inventionis basically an excellent knitting size for water-insensitive yarns, asdiscussed, and equally useful for circular knitting of similar. or heavyfabrics from similar or heavy dem'er'yarns, including monofils, and alsomay be used to advantage with other structures, such as films, staplefiber, spun yarn, mixed yarn, ribbons, etc.

j By reason of the invention, the expeditious knitting of nylon 'yarnsinto such critical fabrics as full-fashioned hosiery is more fullyassured. Orderly and more regular knitting is maintained.

6 Even when knitting at high relative humidities, as is commonly done,or when knitting at uncontrolled humidities which sometimes show greatvariations from day to day or even from hour to 5 hour in some parts ofthe eastern seaboard, the composition of this invention assures regularand excellent knitting with no fouling of the knitting needles orsinkers and no perceptible wear n the needles, even after several daysof operation. It is difficult to define the excellence of the knittinperformance in mathematical language, but it can be stated that thesizing composition of this invention gives as good knitting performanceat 100% humidity as the best previous compositions gave with dryknitting.

The subsequent process steps can be easily carried out and thepercentage of damaged stockings materially decreased. The inventioninvolves no new equipment or altered techniques. The control of theedge-r0lling of the fiat fabric is also entirely satisfactory, as can beseen from a seaming time for 100 stockings of 80 minutes, compared with98 minutes with the best previous composition knit dry as against theknitting according to this invention at 100% humidity. The protection ofthe fabric against snagging and pulled threads during the subsequentprocessing steps is quite satisfactory, taking into consideration theexcellent knitting performance. Based on ,000 stockings carried throughknitting, seaming, boilofi, boarding and drying, the compositions ofthis invention show 10% to 14% pulled threads as against 0% to 20% forthe best previous sizing composition, i. e. polyvinyl alcohol-boricacid. It might be interesting to note in passing that when thesemodified polymers of dioxolane are used by themselves, the percentage ofpulled threads wa 61 an intolerable situation.

As a matter of fact, the resistance of workers to working on nylonstockings in view of their inherent difficulties compared with silk hasbeen finally overcome. Significant to the public is the fact that thecost of stockings bears a close relationship to the percentage ofstockings made that cannot leave the factory because of pulled theattributes of this invention is that this percentage is materiallydecreased.

Since it is obvious that many changes and modifications can be made inthe above-described details without departing from the nature and spiritof the invention, it is to be understood that the invention is not to belimitedthereto except as set forth in the appended claims.

I claim:

1. A yarn-sizing composition comprising a water-sensitive hydroxylatedpolyvinyl resin, boric acid and a polymer of the class which con sistsof modified polymers of dioxolane and alkyl v substituted dioxolanes,said polymer being a water-soluble waxy solid having a molecular weightwithin the range of 500 to 1500 and modified by a member of the classwhich consists of carboxylic acids and esters thereof, the ratio of thetotal amount of said hydroxylated resin and boric acid to the amount ofsaid polymer being within the limits of 65 I35 and 35:65.

2. A yam-sizing composition comprising an aqueous solution of awater-sensitive hydroxylated polyvinyl resin, boric acid and a polymerof the class which consists of modified polymers 4 of dioxolane andalkyl substituted dioxolanes, said polymer being a water-soluble waxysolid having a molecular weight within the range of 500 to 1500 andmodified by a member of the class which consists of carboxylic acids andesters thereof, the ratio of the total amount of said hy-- droxylatedpolyvinyl resin and boric acid to the amount of said polymer beingwithin the limits of 65:35 and 35:65, and the boric acid being presentin an amount of from to 25% based on the weight of the hydroxylatedpolyvinyl resin.

- 3. A yam-sizing composition comprising a partially saponifiedpolyvinyl acetate, boric acid and a polymer of the class which consistsof modified polymers of dioxolane and alkyl substituted d1- oxolanes,said polymer being a water-soluble waxy solid and having a molecularweight within the range of 500 to 1500 and modified by a member of theclass which consists of carboxylic acids and esters thereof, the ratioof the total amount of said polyvinyl acetate and boric acid to theamount of said polymer being within the limits of 65:35 and 35:65.

4.. A yam-sizing composition comprising a partially saponified polyvinylacetate, boric acid and a polymer of the class which consists ofmodified polymers of dioxolane and alkyl substituted dioxolanes, saidpolymer being a water-soluble waxy solid having a molecular weightwithin the range of 500 to 1500 and modified by a member of the classwhich consists of carboxylic acids and esters thereof, the ratio of thetotal amount of said polyvinyl acetate and boric acid to the amount ofsaid polymer being within the limits of 65:35 and 35:65, and the boricacid being present in an amount of from 5% to 25% based on theweight ofthe polyvinyl acetate.

5. A yarn-sizing composition comprising a partially saponified polyvinylacetate, boric acid and polydioxolane sebacate, the ratio of the totalamount of said polyvinyl acetate and boric acid to the amount of saidpolydioxolane sebacate being within the limits of 65:35 and 35 65.

6. A yarn-sizing composition comprising a partially saponified polyvinylacetate, boric acid and polydioxolane sebacate, said polydioxolanesebacate having a molecular weight of about 1500, a hydroxyl number of61.7 and a ratio of combined sebacic acid to combined 1,3-dioxolane 011:8, the ratio of the total amount of said polyvinyl acetate and boricacid to the amount of said polydioxolane sebacate being within thelimits of 65:35 and 35:65.

7. A yarn-sizing composition comprising a partially saponified polyvinylacetate, boric acid and polydioxolane adipate, the ratio 7 of the totalamount of said polyvinyl acetate and boric acid to the amount of saidpolydioxolane adipate being Within the limits of 65:35 and 35:65.

8. A yarn-sizing composition comprising a par tially saponifiedpolyvinyl acetate, boric acid and polydioxolane adipate, saidpolydioxolane adipate having a molecular weight of about 1100, ahydroxyl number of 66.7 and a ratio of combined adipic acid to combined1,3-di'oxolane of 1:10, the ratio of the total amount of said polyvinylacetate and boric acid to the amount of said polydioxolane gdipate beingwithin the limits of 65:35 and 9. A yarn-sizing composition comprising apartially saponified polyvinyl acetate, boric acid and polydioxolanestearate, the ratio of the total amount of said polyvinyl acetate andboric acid to the amount of said polydioxolane stearate being within thelimits of 65:35 and 35:65

10. A yarn -sizing composition comprising a partially saponifiedpolyvinyl acetate, boric acid and polydioxolane stearate, saidpolydioxolane stearate having a molecular weight of about 1200, a

hydroxyl number of 59 and a ratio of combined stearic acid to combined1,3-dioxolane of 1:8, the

ratio of the total amount of said polyvinyl acetate and boric acid tothe amount of said polydioxolane 5 stearate being within the limits of65:35 and 11. A water-insensitive yarn having a size coating comprisinga water-sensitive hydroxylated polyvinyl resin, boric acid and a polymerof the class which consists of modified polymers of dioxolane and alkylsubstituted dioxolanes, said polymer being a water-soluble wax solid,having a molecular weight within the range of 500 to 1500, and modifiedby a member of the class which consists of carboxylic acids and estersthereof, the ratio of the total amount of said hydroxylated resin andboric acid to the amount of said polymer being within the limits of65:35 and 35:65.

12. A water-insensitive yarn having a size coating comprising a.water-sensitive hydroxylated polyvinyl resin, boric acid and a polymerof the class which consists of modified polymers of dioxolane and alkylsubstituted dioxolanes, said polymer being a water-soluble waxy solid,having a molecular weight within the range of 500 to 1500, and modifiedby a member of the class which consists of carboxylic acids and estersthereof, the ratio of the total amount of said hydroxylated polyvinylresin and boric acid to the amount of said polymer being within thelimits of 65:35 and 35:65, and the boric acid being present in an amountof from 5% to 25% based on the weight of the hydroxylated polyvinylresin.

13. A water-insensitive yarn having a size coating comprising apartially saponified polyvinyl acetate, boric acid and a polymer of theclass which consists of modified polymers of dioxolane andalkylsubstituted dioxolanes, said polymer being a water-soluble'waxysolid, having a molecular weight within the range of 500 to 1500, andmodified by a member of the class which consists of carboxylic acids andesters thereof, the ratio of the total amount of said polyvinyl acetateand boric acid to the amount of said polymer be- 45 ing within thelimits of 65:35 and 35:65.

14. A water-insensitive yarn having a size coat-, ing comprising apartially saponified polyvinyl acetate, boric acid and a polymerof theclass which consists of modified polymers of dioxolane 50 and alkylsubstituted dioxolanes, said polymer 'being a water-soluble waxy solid,having a molecular weight within the range of ,500 to 1500,

and modified by a member of the class which consists of carboxylic acidsand esters thereof, the 55 ratio of the total amount of said polyvinylacetate and boric acid to the amount of said polymer being Within thelimits of 65:35 and 35:65, and the boric acid being present in an amountof from 5% to 25% based on the weight of the hydroxylated 6o polyvinylresin.

15. A yarn formed of a synthetic linear polycarbonamide wherein theaverage number of carbons in the segments of the chain separating theamide groups is at least two and having a size coating 65 comprising awater-sensitive hydroxylated polyvinyl resin, boric acid and a polymerof the class which consists of modified polymers of dioxolane and alkylsubstituted dioxolanes, said polymer being a water-soluble waxy solidand having a molecular weight within the range 'of 500 to 1500 andmodified by a, member of the class which con- I sists of carboxylicacids and esters thereof, the ratio of the total amount of saidpolyvinyl resin and boric acid to the amount of said polymer beingwithin the limits of 65:35 and 35:65, and the boric acid being presentin an amount of from which consists of modified polymers of dioxolaneandalkyl substituted dioxolanes, said polymer being a water-soluble waxysolid, having a, molecular weight within the range of 506 to 1500, andmodified by a member of the class which consists of carboxylic acids andesters thereof, the ratio of the total amount of said polyvinyl acetateand boric acid to the amount of said polymer be .ing within the limitsof 65:35 and 35:65.

17. A yarn formed of a synthetic linear polycarbonamide wherein theaverage number of carbons in the segments of the chain separating theamide groups is at least two and having a size I to 25% based on theweight of the polyvinyl acetate.

18. A yarn formed of a synthetic linear polycarbonamide wherein theaverage number of carbons in the segments of the chain separating theamide groups is at least two and having a size coating comprising apartially saponified polyvinyl acetate, boricacidand polydioxolanesebacate,

' the ratio of the total amount of said polyvinyl coating comprising apartially saponifled polyvinyl acetate, boric acid and a poiymer,of theclass which consists of modified polymers of dioxolane and alkylsubstituted. dioxolanes, said polymer being a water-soluble 'waxy solid,having a molecular weight within the range of 500 to 1500, and modifiedby a member of the class which consists of carboxylic acids and estersthereof, the ratio of the total mount of said polyvinyl acetate andboric acid to the amount of said polymer being within the limits of65:35 and 35:65, and the boric acid being present in an amount of fromacetate and boric acid to the amount of said polydioxolane sebacatebeing within the limits of 65:35 and 35:65. v

19. A yarn formed of a synthetic linear polycarbonamide wherein theaverage number of carbons in the segments of the chain separating theamide groups is atdeast two and having a size coating comprising apartially saponified polyvinyl acetate, boric acid and polydioxolaneadipate, the ratio of the total amount of said polyvinyl acetateandboric acid to the amountof said polydioxolane adipate being withinthe limits of 65:35 and 35265.

20. A yarn formed of a synthetic linear polycarbonamide wherein theaverage number of carbons in the segments of the chain separating theamide groups is at least two and having a size coating comprising apartially saponified polyvinyl .acetate, boric acid andpolydioxolane-stearate,

the ratio of the total amount of said polyvinyl acetate and boric acidto the amount of said p0lydioxolane stearate being within the limits of65:35 and :65.

HARRY R. DI'I'I'MAR.

